641 research outputs found

    Critical loads for lead in France: First results on forest soils

    Get PDF
    Within the framework of the United Nation Convention on Long Range Transboundary Air Pollution, France is part of the Working Group on Effect which aims at evaluating the impact of atmospheric deposition on ecosystems by calculating critical loads. The critical loads are the highest deposition of compounds that will not cause chemical changes in soil leading to long-term harmful effects on ecosystem structure and function. A guidance manual for calculation of critical loads for heavy metals (lead and cadmium) has been proposed by the Coordination Center for Effects (executive body of the WGE). French National Focal Center (CNRS and ADEME) aims in this study at evaluating the accuracy of the european methodology for calculation of critical loads for french forest soils. It appears that critical load approach is adapted for France but need to be calibrated at least for calculation of weathering fluxes and determination of critical limits. Stand-still on the contrary is not adequate because of inherent contradictions in the method and too much uncertainties in the transfer functions

    Flood survey of nitrate behaviour using nitrogen isotope tracing in the critical zone of a French agricultural catchment

    Get PDF
    Measurements of δ15N–NO3– were taken in a highly flood-responsive agricultural catchment in the southwest of France to trace the sources and transfer pathways of nitrates during flood events. From January to March 2013, surface water samples were collected every week at the outlet, and four floods were sampled with a high resolution. Sampling was also performed in surface waters and sand lenses from the rest of the basin to trace nitrate sources and processes spatially. Nitrate extractions were performed using a method based on the solubility difference between inorganic salts and organic solutions. The δ15N values were in the range of surface water contaminated by N-fertilisers. Depending on the hydroclimatic event, nitrates resulted from a combination of sources and processes. At the start of the floods, the values of δ15N–NO3– and nitrate concentrations were low, demonstrating the dilution of water with rainwater. During a second phase, the nitrate concentration and the δ15N were higher. Deeper waters and soil solutions were the second source of nitrates. When the water level was low, both nitrate concentration and isotopic composition were high. These values reflected the denitrification processes that occurred in the soil under anaerobic conditions. An analysis of δ15N–NO3– in stream water in a small agricultural catchment was efficient at determining the origin of nitrates during flood events using a simple method

    Evidence of Springwater Acidification in the Vosges Mountains (North-East of France): Influence of Bedrock Buffering Capacity

    Get PDF
    Investigations on springwater acidity were carried out in the Vosges mountains (north-eastern France). Acid or poorly buffered spring and streamwaters were detected in the same area. The proportion of acid springwaters (pH < 5.6) is about 20% among 220 springs. The springwater pH on granite are equally spread between 5.0 and 6.8 whereas on sandstone a majority of springs is in the range 5.6 to 6.2. As a whole, but mainly on sandstone, from the 1960's to 1990's, the shape of the pH distributions shifts toward greater acidity. In the sandstone area, trends in pH, alkalinity, total hardness (corresponding to divalent cations), sulfate and nitrate were considered over the 30 yr period (1963-1996) in relation to the bedrock chemical composition. Kendall seasonal tau coefficients indicate that decreasing trends were significant for the first three parameters. Linear regression on the smoothed mean value revealed 18 and 90% decrease for pH and alkalinity respectively, for springwaters draining poor-base cation sandstone whereas only 8 and 30% decrease respectively, was observed on clay-enriched sandstone. On silica-enriched sandstone, alkalinity began to decrease in the early 70's as well as pH. Loss of alkalinity only occurred in the early 80's for springs draining clay enriched sandstone. This can be interpreted as a titration process by acid atmospheric inputs of the buffering capacity of weathering and exchange processes in the soils and the catchment bedrock. The nitrate presents an increasing step in the early seventies but possibly as a result of change in analytical technics and/or increase in atmospheric inputs mainly resulting from increase in fertiliser inputs in agricultural areas or in car traffic. Surprisingly no change in sulfate was noticed in any groups of springs probably as a result of the adsorption/mobilisation in the soils. These long-term trends in spring waters (1963-1996) confirmed the soil and streamwater acidification trends already mentioned in this region, in relation to acid atmospheric inputs since no climate nor forestry practice changes have been detected over the period. Moreover, in spite of acid atmospheric input reductions, no recovery can presently be detected

    Conceptualizing human resilience in the face of the global epidemiology of cyber attacks

    Get PDF
    Computer security is a complex global phenomenon where different populations interact, and the infection of one person creates risk for another. Given the dynamics and scope of cyber campaigns, studies of local resilience without reference to global populations are inadequate. In this paper we describe a set of minimal requirements for implementing a global epidemiological infrastructure to understand and respond to large-scale computer security outbreaks. We enumerate the relevant dimensions, the applicable measurement tools, and define a systematic approach to evaluate cyber security resilience. From the experience in conceptualizing and designing a cross-national coordinated phishing resilience evaluation we describe the cultural, logistic, and regulatory challenges to this proposed public health approach to global computer assault resilience. We conclude that mechanisms for systematic evaluations of global attacks and the resilience against those attacks exist. Coordinated global science is needed to address organised global ecrime

    Weathering, atmospheric deposition and vegetation uptake: role for ecosystem sensitivity to acid deposition and critical load

    Get PDF
    Critical loads of acidity represent the maximum acceptable atmospheric deposition for an ecosystem type. Two hundred and forty-one ecosystem types have been defined in France using pedologic, geologic and vegetation data. Weathering rate plays the most important part in soil buffering capacity, but for poor weatherable soils, non-marine atmospheric deposition represents up to 80% of base-cation inputs. Base-cation vegetation uptake decreases significantly the buffering capacity in case of high-productivity forests. Ecosystems combining low weathering rate and low non-marine base-cation deposition with high biomass productivity are the most sensitive to acidification

    Rainfall Variability along the Southern Flank of the Bambouto Mountain(West-Cameroon)

    Get PDF
    This paper presents the rainfall variability along the southern flank of the Bambouto mountain. Data were collected from rain gauges, while spatial variability was estimated through daily recorded data. Monthly and annual data were used to draw isohyetes via the triangular method, with linear interpolations between observation points. Results show that rainfall is highly variable along the slope. Daily rainfall amounts range from 0.1 mm to 120 mm. Mean yearly rainfall is 1918.1 mm. Rainfall amount does not have a linear relationship with altitude. Dschang is characterised by abnormally high rainfall. Following a North-South direction, rainfall decreases from Dschang to a Melang-Loung-Djuttitsa axis. From this axis, the gradient reverses as rainfall increases rapidly towards the Mélétan mountain. The existence of the relatively dry zone within the hillside seems to be due to the influence of two air masses. The first is cold and very wet which moves from the Mamfe basin to the summit zone where it starts to warm up as it flows towards Melang and Loung where temperature increases. The second comes from the south to south-east monsoon which is also impoverished during the ascension to higher altitudes. It is also likely that a third air mass from the dry harmattan is involved depending on the position of the ITCZ

    „Um den Bedürfnissen des praktischen Lebens entgegenzukommen“ – ein Einblick in Biografie und Werk William Sterns

    Get PDF
    Im Jahr 2011 wurde die akademische Psychologie in Hamburg 100 Jahre alt. Sie hat sich über einen Zeitraum, der zwei Weltkriege, einen Kalten Krieg und die Transformation vom Kaiserreich über das „Dritte Reich“ zur Demokratie umfasst, in Hamburg nicht nur gehalten, sondern erheblich ausdifferenziert und weiterentwickelt. Der Fachbereich Psychologie dokumentiert anlässlich dieses Jubiläums im hier vorliegenden Band einige der Entwicklungsstufen der akademischen Psychologie in Hamburg. Die Beiträge von Kurt Pawlik, Bernhard Dahme, Manfred Amelang, Frank Rösler sowie Martin Spieß und Tania Lincoln erzählen die Geschichte der akademischen Psychologie in Hamburg aus ganz unterschiedlichen, durchaus subjektiven Perspektiven. Eine Ausnahme bilden die Beiträge von Paul Probst zu den Anfängen der akademischen Psychologie in Hamburg mit Ernst Meumann und William Stern. Den Band beschließt eine unter der Herausgeberschaft von Kurt Pawlik und Bernhard Dahme erstellte Dokumentation der institutionellen und Personalentwicklung der akademischen Psychologie an der Universität Hamburg seit 1950.period of time that encompasses the two World Wars, a Cold War and the transformation from the Empire through the "Third Reich" to democracy, the department has not only remained in Hamburg, but has also differentiated and developed considerably. On the occasion of this jubilee, the Department of Psychology documents in this volume some of the developmental stages of academic psychology in Hamburg. The contributions by Kurt Pawlik, Bernhard Dahme, Manfred Amelang, Frank Rösler, Martin Spieß and Tania Lincoln tell the story of academic psychology in Hamburg from very different, subjective perspectives. Paul Probst\u27s contributions to the beginnings of academic psychology in Hamburg with Ernst Meumann and William Stern are an exception. The volume has been published by Kurt Pawlik and Bernhard Dahme as editors of a documentary on institutional and personnel development in academic psychology at the University of Hamburg since 1950

    Immunostaining for the tumour suppressor gene p16 product is a useful marker to differentiate melanoma metastasis from lymph-node nevus

    Get PDF
    Upon the introduction of extensive sampling protocols of sentinel node biopsies, pathologists are increasingly confronted with small melanoma metastases. Using conventional histology, it proves sometimes difficult or impossible to differentiate small melanoma metastases from lymph-node nevi. Loss of the tumour suppressor gene p16 has been shown to be associated with tumour progression of melanoma. We investigated nevus and melanoma cells for the presence of the product of the gene p16, using immunohistochemistry. All nevus cells, independent of their location (nodal or skin) displayed an extensive nuclear and cytoplasmic staining for p16. In contrast, all cells of melanoma metastases, except one skin metastasis, lacked nuclear staining for p16. These findings indicate that p16 is a reliable marker to distinguish lymph-node nevi from melanoma metastasi

    High levels of air pollution reduce team performance

    Get PDF
    Teams play a key role in tackling complex societal challenges, such as developing vaccines or novel clean energy technologies. Yet, the effect of air pollution on team performance in non-routine problem-solving tasks is not well explored. Here, we document a sizable adverse effect of air pollution on team performance using data from 15,000 live escape games in London, United Kingdom. On high-pollution days, teams take on average 5% more time to solve a sequence of non-routine analytical tasks, which require collaborative skills analogous to those needed in the modern workplace. Negative effects are non-linear and only occur at high levels of air pollution, which are however commonplace in many developing countries. As team efforts predominantly drive innovation, high levels of air pollution may significantly hamper economic development
    • …